The present invention relates to a novel porous fiberglass mat having particular utility as a substrate or carrier for a liquid or fluid - but subsequently hardened or cured-coating.
Fibrous non-woven fabrics, mats and papers have found particular utility where the dimensional stability, fire resistance, and flexual strength inherent in such materials are to be combined with or imparted to a continuous coating of a polymer material. These laminates have found utility as continuous sheet floor coverings and as faced polymer foam insulating boards used in roof and wall insulation in the building industry. When making such laminates, it has been found desirable to use the inherent adhesive characteristics of the curable polymer material to link a fibrous non-woven mat to the cured polymer coating. The polymer coating adheres to the mass of interlocked fibers making up the mat. This results in an integrated structure having the desired features of both the substrate i.e., the mat and the coating i.e., the polymer.
A problem involved with producing many such laminates is strike-through, that is, the inadvertent or undesired seeping through the thickness of the mat by the polymer substance while in its liquid state.
A number of solutions to this strike through phenomenon have been proposed. Most direct is to make the fibrous non-woven mat of such thickness that the time necessary for the liquid material to pass through the thick mat would exceed the time in which the liquid material would take to gel, polymerize or otherwise become non-flowing.
A second approach would be to decrease the porosity of the fibrous mat to arrest or prevent such penetration. One example of the second approach is illustrated by U.S. Pat. No. 4,186,236 wherein a pin-hole free coating of asphalt is provided to one face of a fibrous glass base mat, this coating being applied with conventional coating techniques using a thixotropic asphalt emulsion. The resulting asphalt coating presents a substantially impenetrable barrier to a liquid settable material--in this case the liquid constituents of a polyurethane foam coating.
A third general method of preventing or discouraging strike-through is to alter the surface characteristics of the fibrous structures making up the bulk of the mat in order to decrease the wettability of the fibers to the liquid coating. Such a process is illustrated in U.S. Pat. No. 4,388,366. In this patent a facing sheet comprises glass fibers bonded to each other by a bonding agent. This sheet is subsequently treated with a "non-wicking agent" thereby coating the bonded fibers with a material which prevents or discourages wicking or wetting of the fibrous mass by the liquid such as the liquid foam plastic ingredients.
Applicants have found that, while in each of the above methods a degree of strike-through prevention is achieved, substantial additional materials and/or an additional coating steps are needed to effectuate the desired benefits. The extra cost involved with the additional fibrous material or the extra process step makes the use of the glass fiber mat in particular somewhat less cost competitive with some of the other materials (papers, foils, etc,) available for these facing or substrate applications.